Chapter 1 Sampling scheme

We sampled 4 sites over at least one 24 hr period. We installed 25 ebullition traps across 5 transects in each impoundment. Every 3 hours, we recorded the volume of gas accumulated in each ebullition trap and took a diffusive flux measurement immediately adjacent to 10 if the ebullition traps across the impoundment. To determine impoundment area, I digitized the impoundments using high resolution (0.5 ft) orthoimagery captured during the leaf off period. Pick has a beaver dam on the inlet stream and I delineated only to the beaver dam.

Site Area (km2) Max Depth (m) Mean Depth (m) Residence Time (days) Dates Sampled
Deans 0.0041 3.52 2.03 46 8/16/22 - 8/17/22
8/30/22 - 8/31/22
Sister 3 0.0012 2.27 1.25 20 8/22/22 - 8/23/22
Catfish 0.0018 1.98 0.80 19 9/06/22 - 9/07/22
9/18/22 - 9/19/22
Pick 0.0077 3.80 1.58 45 8/22/22 - 8/23/22

1.1 Dissolved oxygen

We recorded dissolved oxygen every 15 minutes 0.25 m below the surface in every impoundment. From 6/20/22 to 7/13/22, we also recorded dissolved oxygen 0.1m from the bottom of Pick in the deepest location in the impoundment. Because dissolved oxygen was consistently 0 mg/L, we reallocated our oxygen sensors and installed both a top and bottom DO sensor in Sister 3.

1.1.1 Deans

1.1.2 Catfish

1.1.3 Sister

1.1.4 Blue Herron

1.1.5 All impoundments top DO

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Summary of DO during sampling

## # A tibble: 4 × 4
##   site        min_do max_do mean_do
##   <chr>        <dbl>  <dbl>   <dbl>
## 1 Blue Herron  0.043  0.141  0.0495
## 2 Catfish      0.359  7.64   5.54  
## 3 Deans        4.91   7.93   6.32  
## 4 Sister       7.19   9.26   8.40

1.2 Temperature

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You are here for cleaning ### Deans

1.2.1 Catfish

1.2.2 Sister 3

1.2.3 Blue Herron

1.3 PAR

All sensors were submerged ~0.25m below the water surface

1.3.1 Deans

Sensor casing cracked, so no available PAR data for second Deans sampling

8/16/22

1.3.2 Catfish

9/6/22

1.3.3 Pick

#9/13/22

1.3.4 Sister3

#8/22/22

1.4 Dissolved gas concentrations

I sampled for dissolved gas 0.25 m from the surface of the impoundments, 0.1m from the bottom, in the inlet stream, and in the outlet stream. The dissolved gas samples from Catfish on 9/18/22-9/19/22 were not handled properly, thus those values are excluded from the summaries.

## # A tibble: 20 × 7
## # Groups:   Site, Collection.Date [5]
##    Site    Collection.Date Location CH4_avg_umol     CH4_sd CO2_avg_umol CO2_sd
##    <chr>   <chr>           <fct>           <dbl>      <dbl>        <dbl>  <dbl>
##  1 Pick    9/13/2022       top           98.7     3.09             560.    8.69
##  2 Deans   8/31/2022       top            0.980   1.32              62.3   7.88
##  3 Sister3 8/23/2022       top            0.849   0.0111            40.3   4.55
##  4 Catfish 9/6/2022        top            0.586   0.00180          138.    5.69
##  5 Deans   8/16/2022       top            0.583   0.0476           107.    3.11
##  6 Pick    9/13/2022       bottom       126.     60.7              635.  161.  
##  7 Sister3 8/23/2022       bottom         2.89    0.985             70.0  15.2 
##  8 Deans   8/16/2022       bottom         0.883   0.0543            88.9  16.4 
##  9 Catfish 9/6/2022        bottom         0.557   0.0686           164.   49.1 
## 10 Deans   8/31/2022       bottom         0.290   0.0597            36.6   6.79
## 11 Deans   8/31/2022       inlet         16.9     4.77             377.   99.1 
## 12 Pick    9/13/2022       inlet          9.98    1.34             168.    9.29
## 13 Deans   8/16/2022       inlet          9.95    2.86             234.   46.0 
## 14 Catfish 9/6/2022        inlet          0.598   0.197            141.    6.10
## 15 Sister3 8/23/2022       inlet          0.0229  0.0000664         75.2   7.54
## 16 Deans   8/31/2022       outlet         4.31    0.936            153.   44.1 
## 17 Sister3 8/23/2022       outlet         2.62    0.0720            81.8   8.42
## 18 Catfish 9/6/2022        outlet         1.47    0.410            142.    9.15
## 19 Pick    9/13/2022       outlet         0.365   0.170            160.   25.6 
## 20 Deans   8/16/2022       outlet         0.311   0.106             50.2   5.51

1.5 Wind Speed

We took two 15 second averaged windspeed measurements over the course of each diffusive flux measurement. Note different x-axis scales.

1.6 Residence time calculation

I took a point estimate of discharge from the ponds while sampling, but these discharge values gave unrealistic residence times. I instead calculated discharge from a regional regression equation using average annual precipitation and watershed area (Gotvald et al. 2017).